A biosensor is an analytical device for the detection of an analyte that combines a biological component with a physicochemical detector. The biosensor is now being developed for a variety of applications, such as healthcare, food safety, etc.
One of the current biosensors, for example Magnotech platform, works as follows. When a sample is poured into a chamber, the magnetic beads in the chamber begin to capture the target molecules in the sample via antibodies (called ‘Target capture’). Then, a first magnetic field is applied to attract all of the magnetic beads to a detection surface, coated with antibodies, of the chamber (called ‘Magnetic attraction’), wherein magnetic beads capturing the target molecules (i.e., bound magnetic beads) are bound to the detection surface via antigen-antibody reaction, and magnetic beads capturing no target molecule (i.e., unbound magnetic beads) are held at the detection surface via magnetic force. Next, a second magnetic field is applied to pull the unbound magnetic beads away from the detection surface (called ‘Magnetic wash’). An optical method is then used to measure the amount of the bound magnetic beads at the detection surface and thereby the concentration of the target molecules in the sample.
The current biosensor can work with very small sample size, for example 100 μl, and have certain sensitivity for this sample size. However, this small sample size could be the limitation/disadvantage for applications such as food safety. First, the property of food sample determines that the sample size of 100 μl is less representative. Second, the sensitivity requirement in food safety is very high. Thus the small sample size may result in either false negative or longer enrichment time.